The present invention relates to a method and apparatus for determining a prediction of the equalized temperature of a food product prior to the food product reaching its thermal equilibrium. More specifically, this invention is a method and apparatus for predicting such equalized temperature based on the response of the food product to thermal shocks.
The food industry produces a large quantity of standardized food products. In order to control the processes used to make standardized food products the industry is relying to a greater extent on electronic control systems which monitor various food manufacturing processes and input variables in order to control the quality of the food product as well as to minimize waste and decrease costs.
One problem associated with the processing of food items is determination of the equalized temperature of the food item. The need for temperature measurement is particularly acute in the area of food cooking and/or frying systems where high heat transfer rates result in a significantly hotter surface surrounding a cooler core. The goal is to reach a certain equalized temperature for the entire food item which takes a certain amount of time to achieve while also minimizing the amount of energy required to achieve the equalized temperature. Likewise, for cryogenically cooled or frozen foods there is a need to have food items reach a certain equalized temperature specified by the needs of the food item while using the least amount of cryogen.
An intrusive method of temperature determination such as the use of a temperature probe which is inserted into a food item has severe limitations in measuring the equalized temperature of a food item in a continuous food processing environment. The temperature probe must be manually inserted into a food item which cannot then be further processed resulting in waste. Also, the amount of labor needed to monitor a significant number of food items invasively would be cost prohibitive. Furthermore, the actual equalized temperature can only be measured after a certain amount of time passes, perhaps as much as ten or twenty minutes, and, therefore, a large number of food items could be incorrectly processed before an error in the equalized temperature is detected.
Another prior art method of temperature measurement such as a single infrared sensor would only be capable of measuring the surface temperature of the product and not the equalized temperature throughout the product.
In light of the foregoing, there is a need in the art for a method and apparatus which enables a food processor to predict or estimate the equalized temperature of a food item in a food processing line in a continuous manner without diverting actual food items from the processing line and using intrusive manual temperature testing. Furthermore, the method and apparatus need to allow the food processor to predict the equalized temperature of the food items immediately after a thermal shock is applied, i.e., cooking or cooling, , rather than after they have actually reached their equalized temperature, so that problems with the cooking process or cooling/freezing cryogenic process can be corrected in real-time.
Accordingly, the present invention is directed to a method and apparatus for continuous prediction of the equalized temperature of a food item during processing.
Furthermore, the invention is directed to a method and apparatus for estimating such equalized temperatures in conditions of variable air flow and variable temperatures found in food processing.
In addition, the invention is directed to a method and apparatus which is non-intrusive and will not cause damage to food items.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes an apparatus having an infrared sensor for measuring the surface temperature of a food item and means for applying a heat transfer shock of known quantity to the food item for a set length of time. At least two measurements of the surface temperature of the item are taken at specific times after the initial thermal shock and the equalized temperature of the food item is mathematically predicted from the two measurements.
In one aspect of the present invention the thermal shock and surface temperature measurement process is repeated in order to increase the accuracy of the predicted temperature.
In another aspect of the present invention multiple surface temperature readings are taken after each application of thermal shock with feedback mechanisms to alter the magnitude of the thermal shock.
In a further aspect of the present invention a plurality of infrared sensors are mounted over a food processing line so that food items pass under the plurality of sensors and an equalized temperature is predicted for a food item based on the readings from the plurality of sensors.
In a still further aspect of the invention the information as to the predicted equalized temperature of the food product is logged in a computer database for use by the food processing system and for purposes of altering the magnitude of additional thermal shocks to the food items.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.